Stabilization of tetraalkyl lead and compositions containing the same



in a few hours course,"imparted to the motor fuel upon blendi Patented Mar. 2, 1948 STABILIZATION F TETRAALKYI. COMPOSITIONS, CONTAININGTHEW Harold Von Brameiand Albert 0.;

Klngspo Tenn.,'assignorstoliastman Kodak Rochester, N. Y... a corporation of rt, Company. New Jersey No Drawing. Application sfl'lfll N0. 534.9

This invention relates to the stabilization oftetraalkyl lead, normal impurities, and to the stabilization of tetraalkyl lead compositions containing hydro- Icaarbons and/or-halogen derivatives of hydrocar ons. i 1 a It is known that ordinary commercial tetraalkyl lead compounds, particularly tetraethyl lead, decompose slowly on standing with the formation of a precipitate, and that this decomposition is accelerated in the presence of halogen derivatives of hydrocarbons. This decomposition also takes place in hydrocarbon motor fuels which contain tetraethyl lead compounds. Ordinarily, tetraalkyl lead compounds, such as tetraethyl lead are incorporated in gasoline in the form of a liquid called "ethyl fluid" which usually is a solution containing a mixture of tetraethyl lead LEAD AND varies.

Mayld 1544. so

unmixed with anything but as.

and a halogenated hydrocarbon, such as ethylene dibromide or ethylene dichloride, or both. Sometimes a small amount of dye is present in the "ethyl fluid" to impart a distinctive color. The "ethyl fluid" is, of course, added to the gasoline to produce an improved anti-knock rating, In some cases, only a relatively small amount of "ethyl fluid" is added, shut sometimes, as with certain aviation grade of gasoline, a larger amount is used. Motor fuels to which a relatively large amount of tetraethyl lead'or other tetra-' alkyl lead compound has been added, are often referred to as "heavily leaded gasolines.

Hydrocarbon motor fuels containing such tetraalkyl lead compounds tend to develop a hazyappearance upon standing, especially when contact between these fuels and the oxygen of the air occurs, as is inevitable in the ordinary bane dling and storage of commercial motor fuels; Perceptible haziness may and after longer periods of time, the haziness may become very marked and precipitation may occur. These hazing and precipitation phenomena sometimes occur in the'ethyi fluid itself, and the haze or precipitate is, of D8 the hazed "ethyl fluid with the fuel. The formation of haze and precipitate in gasoline is objectionable from two standpoints. One

involves the reaction of the customer, since in-' become apparent withvariably the customer prefers aproduct which is clear and transparent. The second and more important objection is that a reduction in octane rating often develops with these haze precipitation phenomena and the precipitate may tend to clog the carburetor system of the combustion en ine in which the fuel is used.

It is known that this decomposition of tetraalkyl lead compounds can be retarded by means and particularly in hydrocarbon motor fuels containing tetraalkyl lead compounds, it has been proposed to employ the amines in the form of their salts with long-chain fatty acids, 1. e. fatty acids containing a lipophilic group. e. g. oleic. stearic or lauric,acids. This type of is not always a desirable addition to motor fuels, particularly fuels containing unstable oleflnic hydrocarbons and which have been inhibited against gum formation, because many gum inhibitors are adversely affected by the presence oi acidic substances.

We have now found that the decomposition of tetraalkyl lead compounds can be retarded by incorporating in the tetraalkyl lead, compounds or compositions containing the same an aromatic compound which is a derivative of a phenylenediamine in which one hydrogenatom of each amino group is replaced by a secondary or a tertiary alkyl group. The secondary alkyl or tertiary alkyl groups (which all contain at leastis entirelyunexpected since the corresponding.

simple primary alkyl derivatives, e. g. N,N'-dimethyl-p-phenylenediamine do not have this effect and, in fact, tend to promote the formation of haze, especially in motor fuels.

The Nflf-di-secondary alkyl-p-phenylenedi amines exert an additional eflect on hydrocarbon motor fuels, if the motor fuels are of a character which tend to deteriorate and form gum. These secondary alkyl derivatives have a high gum-inhibiting effect. Very often when gasolines, which are only relatively stable to oxygen absorption and consequent gum formation, are treated with tetraalkyl lead compounds. a decrease in stability results. The compounds. known to the prior art for the stabilization of concentrated tetraalkyl lead solutions have no ability to prevent this decrease. Conversely, the majority of potent compounds which can be added to motor fuels to compound i retard or inhibit oxygen absorption and gum formation are'lncompatible with concentrated tetraalkyi lead solutions. It is unusual to find a compound which is both a good stabilizing agent for concentrated tetraalkyl lead solution and also a potent gum inhibitor. When this dual role is desired of the N,N'-di-alkyl-p-phenylenediamine, the amount incorporated in the ethyl fluid is somewhat greater than is required for stabilization of the concentrated solution so that by the addition of the usual amount of the concentrate to motor fuels, a suitable stabilizing amount of N,N-di-alkyl-p-phenylenediamine will be incorporated in the motor fuel. Usually from 1 to 10 per cent by weight, based on the tetraalkyl lead, of N,N'-di-alkyl-p-phenylenediamine is sufficient, to stabilize the concentrated solutions of lead tetraalkyl against haze formation and precipitation; and this concentration will give in the motor fuel a concentration of phenylenediamine derivative of vfrom 0.001 per cent to 0.01 per cent by weight, based on the motor fuel, depending upon the amount of lead tetraalkyl solution which is added to the motor fuel. A concentration of 0.001 per cent to 0.01 per cent of phenylenediamine derivative in'the motor fuel is ordinarily sufilcient to retard haze formation induced by the lead tetraalkyl, as well as to retard gum formation.

In practicing our invention, we add an amount of the phenylenediamine derivative to the tetra- 'aikyl lead compound itself, or to a mixture of the tetraalkyl lead compound and oneor more halogenated hydrocarbons. In some instances it is desirable to replace a portion of the halogenated hydrocarbon with a solvent, such as benzol or naphtha, to enhance the solubility of the N,N'-di-alkyl-p-phenylenediamine in the concentrated tetraalkyl lead solution. In the case of N,N'-di.-secondary butyl-p-phenylenediamine the use of such solvents is not necessary. Or, we can add the phenylenediamine derivative to a motor fuel containing a tetraalkyl lead compound or we can add the phenylenediamine derivative to a motor fuel to which is then added the tetraalkyl lead compound. s

By the term "hydrocarbon motor fuel, we mean not only motor fuels consisting tirely of hydrocarbons, but also motor fuels con aining hydrocarbons and appreciable amounts of other combustible substances, such as alcohols. By v way of description of our-invention, the following illustrative examples are given, but it will be understood that other embodiments exist and may be practiced without departing from the spirit of the invention:

' EXAMPLE I V In an accelerated storage test, in which the samples were exposed to dififuse sunlight, to 99 grams of commercial ethyl fiuid" per cent by weight of lead tetraethyl in ethylene dibromide) was added 1 gram of N,N'-di-secondary butyl-p-phenylenediamine. This amount of base will be found suiiicient to prevent the development of haze or precipitate indefinitely. A simisample of ethyl fluid" containing no tive of a p-phenylenediamine in which one hydrodi-secondary butyl-p-phenylenediarnine. developed an appreciable amount of yellow precipitate in 9 days storage in a closed container.

EXAMPLE II Two samples of commercial gasoline were treated with ethyl fluid" (60 per cent by weight of lead tetraethyl in ethylene dibromide) to yield Table Precipitation Gasoline Time A B C Hrs. Pennsylvania Straight Run 16 Heavy. None.. None. Texas Aviation Base Stock....... 16 0.. .do Do.

Likewise, other concentrated or dilute solutions of lead tetraalkyl compounds in solvents, such as benzene (benzol) toluene, naphtha, hexanes, heptanes, octanes, nonanes, carbontetrachloride, chloroform,,isopropyl benzene or di-isopropyl ether, for example, or in gasoline which is substantially stable and does not tend to form appreciable gum upon storage, or in cracked gasoline, can be stabilized against haze formation or precipitation by means of N,N'-di-secondary alkyl-p-phenylenediamines or N,N'-di-tertiary alkyl-p-phenylenediamines. Either symmetrical or unsymmetrical phenylenediamine derivatives can be employed. Thus, the symmetrical derivative N ,N'-di-tertiary butyl-p-phenylenediamine or the unsymmetrical derivative N-secondary butyl-N'- isopropyl-p-phenylenediamine can be employed instead of N,N'-di-secondary butyl-p-phenylenediamine. N-secondary butyl-N'-isopropyl-pphenylenediamine is described in the copending application of H. Von Bramer and L. G. Davy,

' Serial No. 493,762, filed July '7, 1943, now Patent No.- 2,381,015, dated August 7, 1945.

What we claim as our invention and desire to be secured by Letters Patent of the United States is:

1. A hydrocarbon motor fuel which is substantially stable and does not tend to form appreciable gum upon storage containing a tetraalkyl lead compound, a halogenated hydrocarbon lead scavenger and, as a haze retarder, a small amount of an aromatic compound which is a derivative of Gp-phenylenediamine in which one hydrogen 4 atom of each amino group is replaced by an alkyl group selected from the group consisting of seca ondary and tertiary alkyl groups.

2. A hydrocarbon motor fuel which is substantially stable and does not tend to form appreciable gum upon storage containing tetraethyl lead, a halogenated hydrocarbon lead scavenger and, asa haze retarder, from 0.001 to 0.01 percent based on the weight of the hydrocarbon motor fuel of anaromatic compound which is a derivagen atom of each amino group is replaced by an alkyl group selected from the groupconsisting of secondary and tertiary alkyl groups,

3. A hydrocarbon motor fuel which is substantially stable and does not tend to form appreciable gum upon storage containing a tetraalkyl lead compound. a halogenated hydrocarbon lead scavenger and. as a haze retarder, from 0.001 to access:

0.01 percent based on the weight 01 the hydrocarbon motor iuel oi N,N'-di-secondary butyl-pphenylenediamine.

4. A hydrocarbon motor fuel which is substantially stable and does not tend to form appreciable gum upon storage containing tetraethyl lead, a halogenated hydrocarbon lead scavenger and, as a haze retarder, from 0.001 to 0.01 percent based on the weight of the hydrocarbon motor fuel of N,N'-di-secondary butyLp-phenylenediamine.

5. A hydrocarbon motor fuel which is substantially stable and does not tend to form appreciable gum upon storage containinglead tetraethyl, a halogenated hydrocarbon lead scavenger and, as a haze retarder, from 0.001 to 0.01 percent based on the weight of the hydrocarbon motor fuel 01' N,N'-di-tertiary butyl-p-phenylenediamine.

6. A hydrocarbon motor fuel which is substantially stable and does not tend to form appreciable gum upon storage containing lead tetraethyl, a halogenated hydrocarbon lead scavenger and, as a haze retarder, from 0.001 to 0.01 percent based on the weight of the hydrocarbon motor fuel of N,N'-di-isopropyl-p-phenylenedia'mine.

7. A tetraalkyl lead compound containing, as a haze-retarder, from 1 to 10 percent based on the weight of the tetraalkyl lead compound of an aromatic compound which is a derivative of a pphenylenediamine in which one hydrogen atom of each amino group is replaced by an alkyl group selected from the group consisting of secondary and tertiary alkyl groups.

8. Tetraethyl lead containing, as a haze retarder, from 1 to 10 percent based on the weight of the tetraethyl lead of an aromatic compound which is a derivative-of a p-phenylenediamine in which one hydrogen atom of each amino group is replaced by an alkyl group selected from the group consisting of secondary and tertiary alkyl groups.

9. A tetraalkyl lead compound containing, as a haze retarder, from 1 to 10 percent based on the weight of the tetraethyl lead of N,N'-di-secondary I butyl-p-phenylenediamine.

10. Tetraethyl lead containing, as a haze retarder, from 1 to 10 percent based on the weight 6 oi the tetraethyl lead of N,N'-di-secondary butyl= p-phenylenediamine.

11. A composition consisting of tetraethyl lead. a

diamine in which one hydrogen atom of eachamino group is replaced by an alkyl group selected from the group consisting of secondary and tertiary alkyl groups.

12. A composition consisting of tetraethyl lead, a. halogenated hydrocarbon lead scavenger and, as a haze retarder, from 1 to 10 percent based on the weight of the lead tetraethyl of N,N'-disecondary butyl-p-phenylenediamine.

13. A hydrocarbon motor fuel which is substantially stable and does not tend to form appreciable gum upon storage containing tetraethyl lead and, as a haze retarder, from 0.001 to 0.01 percent based on the weight of the hydrocarbon motor fuel of an aromatic compound which is a derivative of a p-phenylenediamine in which one hydrogen atom of each amino group is replaced by an alkyl group selected from the group consisting of secondary and tertiary alkyl groups.

14. A- hydrocarbon motor fuel which is substantially stable and does not tend to form appreciable. gum upon storage containing tetraethyl lead and, as a haze retarder, from 0.001 to 0.01 percent based on the weight of the hydrocarbon motor fuel of N,N'-di-secondary butyl-p-pheny1- enediamine.

HAROLD VON BRAP'IER. ALBERT C. RUGGLES.

- REFERENCES CITED The following references are of record in thefile of thispatent:

UNITED STATES PATENTS 

